Holding or cooking oven

ABSTRACT

An oven for maintaining cooked foods at temperatures suitable for serving the foods or even for cooking foods has a cabinet containing multiple heat sinks of channel-shaped configuration. The ends of the heat sinks open out of the cabinet, so that any heat sink may receive a tray of food from either the front or back of the cabinet. The interior surface of the heat sinks generally conform to the cross-sectional shapes of the trays, so that the heat sinks lie along the bottoms and sides of the trays. The heat sinks have a heating elements extended along their sides and bottoms for elevating the temperature of the heat sinks and directing heat into the trays within the heat sinks. In addition, each heat sink also contains a cover which may close the top of the tray in the heat sink and thereby retard the escape of moisture from the tray or may vent the interior of the tray.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 09/538,761, filedMar. 30, 2000, now U.S. Pat. No. 6,175,099, which is acontinuation-in-part of application Ser. No. 09/282,313 filed Mar. 31,1999, now abandoned.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

This invention relates in general to ovens and more particularly to anoven for maintaining foods at temperatures suitable for serving or foreven cooking foods.

Most restaurants which specialize in serving cooked food rapidly—indeed,essentially with the placement of an order—do not have the capacity toprepare large quantities of food on demand. Thus, traditional mealtimes, particularly the noon hour, place severe demands on theserestaurants. Typically, the so-called “fast food” restaurant willprepare some cooked food in advance of a meal time and keep that foodwarm in a holding oven. Then, during a meal time when the demand isgreatest, it will use the food previously cooked.

Some cooked foods, such as hamburger patties, should be held at elevatedtemperatures only in a moist environment, since these foods, whendepleted of their moisture content have poor taste and texture. Othercooked foods, such as breaded chicken or fish fillets, should be storedsuch that moisture may escape, so that they remain crisp. While it isconvenient to store different foods at the same location, the flavor ofone food should not transfer to another food. Moreover, irrespective ofthe food, the temperature at which it is stored must remain high enoughto prevent bacterial contamination, and this generally requires holdingthe food at temperatures in excess of about 150° F. Holding ovens thatare currently in use in fast food restaurants do not fully satisfy theserequirements.

The holding ovens of current manufacture accept trays containing thecooked foods. The typical oven has a cabinet containing storage spaceswhich are accessible from both the front and rear of the cabinet, sothat a tray containing cooked food may be placed into a storage space atone face of the cabinet and withdrawn at the other face. Each storagespace has a heated platen along its top and also preferably at itsbottom, and these platens transfer heat to the trays. The cabinet alsocontains a mechanism for closing the upper ends of the trays to preventmoisture from escaping. In one type of holding oven this mechanismresides in making the spacing between a heated platen on which the trayrests and the heated platen which overlies the tray about equal to theheight of the tray, so that the upper margin of the tray lies along andessentially against the overlying platen, thus in effect closing thetray. See U.S. Pat. No. 5,724,886. Another type of holding oven supportsthe tray on a resilient grate which urges a tray upwardly against anoverlying heated platen, thereby effecting a seal with the overlyingplaten. See U.S. Pat. No. 5,783,803. These ovens are difficult to cleanand do not efficiently concentrate the heat at the trays where it isneeded. As a consequence, the food is often held at a temperature lessthan optimum. Sometimes, the spaces in these ovens hold trays with theirtops open and this leads to a transfer of flavors between multiple traysin any one space. In any event, ovens of current manufacture have thecapacity to store foods for only very limited periods of time.

BRIEF SUMMARY OF THE INVENTION

The present invention resides in an oven having a channel-shaped heatsink which is heated by a heater. The heat sink has a storage cavitywhich generally conforms to the shape of a tray or other food containerreceived in the cavity. As such, the heat sink concentrates the heatgenerated by the heater at the tray so as to efficiently maintain thefood in the tray at a temperature suitable for serving. The heat sinkmay have a cover for closing the top of the tray within it. Where theoven contains multiple heat sinks, these heat sinks are isolated fromeach other to prevent the flavor of the food in one from transferring tofood in another.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification andwherein like numerals and letters refer to like parts wherever theyoccur:

FIG. 1 is a front and top perspective view of a holding oven constructedin accordance with and embodying the present invention, with one of thecovers and one of its trays shown removed;

FIG. 2 is a top and rear perspective view of the oven;

FIG. 3 is a transverse sectional view of two heat sinks, one having itscover in its sealing position and the other having its cover in theventing position;

FIG. 4 is a fragmentary sectional view taken along line 4—4 of FIG. 3;

FIG. 5 is an exploded perspective view of a heat sink, the cover for theheat sink, and a tray;

FIG. 6 is a perspective view of a modified cover.

FIG. 7 is an exploded perspective view of the heat sink, a modifiedcover for the heat sink, and a modified tray; and

FIG. 8 is a fragmentary longitudinal sectional view of the modified trayof FIG. 7 fitted beneath the modified cover of FIG. 7.

Corresponding reference numerals will be used throughout the severalfigures of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, an oven A (FIGS. 1&2) holds multipletrays B in which precooked food is placed and held for limited times,indeed, several hours in the case of some foods. The oven A and thetrays B, which are used with it, will accommodate a variety of foodstypical of those served in fast food restaurants. Among those foods arecooked hamburger patties, ham, bacon, sausage, onion rings, Frenchtoast, fish fillets, chicken fillets and biscuits. Thus, the trays Bconstitute food containers. The oven A heats the trays B from theirbottoms as well as their sides. Moreover, one who places a tray B in theoven A has the option of closing the top of the tray B so as to retainmoisture in the tray B or leaving the top open so that moisture mayescape from the tray B.

Considering the trays B first, they are preferably molded from a polymerthat is capable of withstanding the temperatures maintained in the ovenA, although trays B of stamped metal will suffice as well. In any event,such a tray B has (FIGS. 3-5) a flat bottom wall 2 and also side walls 4and end walls 6 that merge with the bottom wall 2 at corners 8 ofgenerous radius. The side walls 4 and end walls 6 flare outwardlyslightly and each has an offset portion 10 near its upper end. Theoffset portions 10 of the walls 4 and 6, along their upper margins,merge into a rim in the form of a peripheral lip 14 which projectslaterally outwardly and, beyond the side walls 4, turns slightlydownwardly at a depressed edge 16 (FIG. 3). The lip 14 has a flat uppersurface 18 that lies in a common plane along the entirety of the lip 14.At the end walls 6 the lip 14 merges into handles 20 which lie below theplane of the upper surface 18. Similar trays see widespread use in fastfood restaurants.

The oven A includes (FIGS. 1&2) a cabinet 26 having a front panel 28, arear panel 30, end panels 32, and a top panel 34. The front panel 28 andrear panel 30 contain openings 36 which conform generally to thecross-sectional configuration of the trays B, but are slightly wider andsomewhat taller. The openings 36 are arranged in several tiers, and forevery opening 36 in the front panel 28 an opening 36 in the rear panel30 aligns with it. The cabinet 26 at each tier of openings 36 also has(FIGS. 3 and 4), an upper pan 38 that extends through it above theopenings 36 and a lower pan 40 that extends through it below theopenings 36. The upper pan 38 has a peripheral lip 41 which projectsupwardly and imparts rigidity to the pan 38. The pan 38 carries channels42 which extend between the front and rear panels 28 and 30 in theregions between the openings 36. More channels 42 lie beyond the twoendmost openings 36 as well. The channels 42 are attached firmly to thepan 38 and open downwardly. The lower pan 40 for each tier has lips 43that project upwardly and turn inwardly and, beneath the inwardly turnedportions, has rigidifying members 44. The space between the upper andlower pans 38 and 40 for each tier of openings 36 is occupied by severalheat sinks 46 one for each pair of aligned openings 36 in the tier.

Each heat sink 46 is formed from a substance that conducts heat well,aluminum being preferred. When formed from aluminum, the heat sinks 46may be produced as extrusions or castings or they may even be producedby machining. Irrespective of how it is produced, each heat sink 46possesses (FIG. 5) a channel-like configuration in that it is open atboth ends and at its top and closed along its two sides and bottom. Thisleaves the heat sink 46 with a cavity 48 that extends the full length ofthe heat sink 46. The open ends of the cavity 48 align with openings 36in the front and rear panels 28 and 30 of the cabinet 26, so that thecavity 48 of the heat sink 46 is easily accessible from the exterior ofthe oven A. The cavity 48 generally conforms to the exteriorcross-sectional configuration of any tray B.

More specifically, each heat sink 46 includes (FIGS. 3&5) a bottom wall50 and side walls 52 which are formed integral with the bottom wall 50and project upwardly from it. The bottom wall 50 is of uniformthickness, it being about {fraction (3/16)} in. thick, and has a flatbottom surface 54 and a flat top surface 56. In contrast, the two sidewalls 52, while being mirror images of each other, have somewhat variedthickness. Each side wall 52 has a lower region 58 that generallycorresponds in height to the height of a tray B. The lower region 58 hasa flat outside surface 60 and a contoured inside surface 62 that mergeswith the flat top surface 56 of the bottom wall 50 at a curved corner64. Immediately above the corner 64, the inside surface 62 flaresoutwardly slightly, then after undergoing a more abrupt change indirection, extends vertically for a lesser distance. The spacing betweenthe inside surfaces 62 for the side walls 52 of the heat sink 46 isslightly greater than the width of the tray B measured across of theoutside surfaces of its side walls 4. Moreover, the inside surfaces 62of the side walls 52 on the heat sink 46 generally conform inconfiguration to the outside surfaces for the side walls 4 of the trayB. When the tray B is inserted into the heat sink 46 with the bottomwall 2 of the tray B resting in the flat top surface 56 of the bottomwall 50 for the heat sink 46, the side walls 4 of the tray B, despitetheir contoured configuration, are close to the inside surfaces 62 onthe side walls 52 of the heat sink 46. Generally, the spacing at anyelevation between the inside surfaces 56 on side walls 52 of the heatsink 46 should be no more than about 1.0 in. larger than the spacingbetween the side walls 4 of the tray B at the outside surfaces of thoseside walls 4. Thus, when the tray B is centered in the cavity 48 of theheat sink 46, a clearance of no more than about 0.5 in. exists betweenthe inside surfaces 62 of the side walls 52 for the heat sink 46 and theoutside surfaces in the side walls 4 of the tray B. Preferably, when thetray B is centered, the clearance is about 0.015 in. The curved corners64, where the flat bottom surface 54 and contoured inside surfaces 62 ofthe heat sink 46 merge, lie opposite, yet close to, the corners 8 of thetray B.

The lower region 58 of each side wall 52 for the heat sink 46 mergesinto an upper region 66 at an offset 68. The upper regions 66 extendvertically and by reason of the offsets 68, the spacing between theupper regions 66 exceeds the spacing between the lower regions 58.Indeed, that spacing exceeds the width of the tray B at its peripherallip 14. The contoured inside surfaces 62 on the lower regions 58 of theside walls 52 rise to flat horizontal shoulders 70 which extend over theoffsets 68 and out to the upper regions 66. The shoulders 70 lie in aplane that is parallel to the top surface 56 of the bottom wall 52, andthe distance between the shoulders 70 and the top surface 56 is slightlyless than the distance between the lower surface of the bottom wall 2for the tray B and the undersurface of the lip 14 at the side walls 4which undersurface is at the depressed edge 16. Thus, when the tray Brests on the bottom wall 2 of the heat sink 44, the depressed edge 16 ofthe lip 14 beyond each side wall 4 lies slightly above the shoulders 70.The lip 14 remains well below the upper edges of side walls 52 for theheat sink 46.

Those upper edges lie along the upper regions 66 of the side walls 52for the heat sink 46, and here the upper regions 66 are enlargedslightly and received in the channels 42 that are attached to the upperpan 38 for the tier in which the heat sink 46 lies (FIG. 3). The bottomwall 50 of the heat sink 46 at its ends rests on the inwardly turnedportions of the lips 43 for the lower pan 40. (FIG. 4) to which it isfastened. Thus, the heat sinks 46 for any tier are captured between theupper and lower pans 38 and 40 for the tier. The channels 42 confine theheat sinks 46 of the tier laterally, whereas the front and rear panels28 and 30 confine them longitudinally. In short, the heat sinks 46 arefixed in position in the cabinet 26.

Each heat sink 46 is fitted with a heater which may take the form of aflexible heating element 76 of the electrical resistance type. Itextends almost the full length of the heat sink 44, covering the flatbottom surface 54 of the bottom wall 50, the corners between the bottomwall 50 and side walls 52, and the flat outside surfaces 60 on the lowerregions 58 of the side walls 52. It even curves outwardly along thebottom surfaces of the offsets 68 in the side walls 52. To thesesurfaces the heating element 76, which is preferably film-etched, isbonded, preferably with a silicone adhesive capable of withstanding theelevated temperatures produced by the heating element 76. In thisregard, the heating element 76 should produce enough heat and reach atemperature high enough to elevate the temperature of the heat sink 46along the top surface 56 of its bottom wall 50 and along the contouredinside surfaces 62 of its side walls 52 to a temperature suitable formaintaining food within the tray B that occupies that heat sink 46 atany desired temperature. Where the oven A serves as a holding oven, thattemperature keeps the food warm enough for serving and warm enough toprevent bacterial contamination. Where the oven A functions as a cookingoven, that temperature is hot enough to actually cook the food.

Other types of heaters may be used as well. For example, the heater maytake the form of resistance type heating rods embedded in the bottomwall 50 and in the lower regions 58 of the side walls 52. Steam or hotwater may be circulated through channels in the bottom wall 50 and lowerregions 58 of the side walls 52 to maintain the heat sink 46 at anelevated temperature, in which case the channels and the fluid thatflows within them become the heater. On the other hand, if the heat sink46 is formed from a ferrous material, an induction heating device may beused to elevate the temperature.

Behind the side walls 52 of each heat sink 46 and beneath its bottomwall 50, as well, the cabinet 26 is packed thermal insulation 78. Thelower pans 40 in the cabinet 26 support the insulation 78 and preventthe insulation 78 for any one tier of heat sinks 46 from dropping intothe heat sinks 46 of the tier below.

In addition to its heating element 78, each heat sink 46 is equippedwith a cover 80 that rests on the shoulders 70 of its offsets 68 andgenerally occupies the space between the upper regions 66 of its sidewalls 52. The cover 80 includes a pair of vertical legs 82 and a crosswall 84 that extends between and is attached to the vertical legs 82.Indeed, the cross wall 84 is joined to the vertical legs 82 between thelongitudinal edges of the legs 82, it being offset closer to onelongitudinal edge of each leg 82 than the other. However, near its endsthe cross wall 84 flares away from the edges to which it is closest. Thewidth of the cross wall 84 slightly exceeds the width of the tray B atits lip 14. The height of the vertical legs 82 is slightly less that theheight of the upper regions 66 of the two side walls 52 for the heatsink 44. These dimensions enable one to easily slide the cover 80 intoand out of the upper region of its heat sink 44.

The configuration of the cover 80 is such that it may assume twopositions within the space between the upper regions 66 of the sidewalls 52 for the heat sink 44—a closing position (FIG. 3-left) and aventing position (FIG. 3-right). In the closing position the cross wall84 of the cover 80 rests on the upper surface 18 of the lip 14 of thetray B, or else lies slightly above the upper surface 18 of the lip 14.In either arrangement the cross wall 84 serves as a closure for the trayB. Where the cross wall 84 actually rests on the lip 14 the legs 82project downwardly almost to the flat horizontal shoulders 70 of theheat sink 46, but do not contact the shoulders 70. The lower margins ofthe legs 82 lie between the lips 14 on the tray B and the upper regions66 of the side walls 52 for the heat sink 46. When the tray B is removedfrom the heat sink 46, the legs 82 of the cover 80 drop downwardly andrest on the shoulders 70 of the heat sink 46. But the ends of the crosswall 84 flare upwardly, leaving enough space between the shoulders 70and those flared ends to accommodate the handles 20 of a tray B. On theother hand, where the cross wall 84 lies slightly above the uppersurface 18 on the lip 14, the legs 82 project downwardly to and actuallyrest on the flat horizontal shoulders 70 of the heat sink 46 with thelip 14 on the tray B being between the regions of contact. A clearanceranging up to 0.375 in. exists between the bottom of the cross wall 84and the upper surface 18 on the lip 14. The legs 82 extend up to andnearly contact the overlying upper pan 38 of the cabinet 26. In theventing position the cover 80 is reversed. Its legs 82 rest on theshoulder 70 of the heat sink 46 outwardly from the peripheral lip 14 ofthe tray B, but the cross wall 84 lies well above the peripheral lip 14and the handles 20. This leaves an open space of at least 0.375 in.between the cross wall 84 of the cover 80 and upper surface 18 on thelip 14 of the tray B at each end wall 6 of the tray B, and moisture fromthe tray B may escape through these spaces.

At the sides of the openings 36 in the front panel 28 and rear panel 30,the cabinet 26 is fitted with pivotal stops 88 of the triangularconfiguration. Each triangular stop 88 serves two openings 36. It pivotsat one of its apices, with the pivot axis being slightly above, butotherwise between, the two openings 36 that the stop 88 serves. Theother two apices project beyond the upper regions 66 of the nearby sidewalls 52 for the heat sinks 46 at those openings 35. As such, thoseother apices project past the ends of the openings 36, but not across,the openings 36.

The free apices of the stops 88 lie beyond the ends of the vertical legs82 for the covers 80 and retain the covers 80 in the upper regions ofthe heat sinks 46. However, to reverse a cover 80 and thereby change itsposition, the stop 88 at the heat sink 46 in which the cover 80 fits, ispivoted away from the opening 36 at that heat sink 46 so as to no longerblock the opening 36. While the stop 88 is held away from the opening36, the cover 80 is removed and reversed. Then the cover 80 is insertedback through the opening 36 in the reversed position. Once the cover 80is fully within the heat sink 44, the stop 88 is released, and itassumes its normal position blocking the end of the opening 36 andthereby retaining the cover 80 in the heat sink 46.

Finally, the cabinet 26 contains electrical controls 92 which controlthe temperature at which the heating elements 78 of the sinks 46operate. A separate control 92 exists for each tier of heat sinks 44.However, the controls 92 may be such that each heat sink 46 iscontrolled individually

The oven A normally awaits use in a restaurant with some of its covers80 in the sealing position and the remainder of its covers 80 in theventing position. As a meal time approaches, the employees of therestaurant cook various foods for which the restaurant expects toreceive orders during the meal time. Immediately after these foods areprepared, they are placed in the trays B, each food being assigned to adifferent tray B. Some of these foods, such as hamburger patties, loosetheir taste and texture with loss of moisture. Others, such as friedchicken fillets, biscuits, and eggs become soggy if stored in anabundance of moisture. The trays B which contain foods that must remainmoist are placed in heat sinks 44 having their covers 80 in the closingposition (FIG. 3-left). The trays B containing foods which must remaincrisp are placed in heat sinks 44 in which the covers 80 are in theventing position (FIG. 3-right). Each heat sink 44 directs heat throughthe bottom wall 2 and side walls 4 of the tray B that is within it, andthe heat keeps the food in the tray B warm—indeed, warm enough toprevent bacterial contamination and warm enough to serve to patrons ofthe restaurant when the demand arises, all with the flavor and texturepreserved.

To insert a tray B into a heat sink 44 having its cover 80 in theclosing position, the restaurant employee brings the tray B to the rearpanel 30 of the cabinet 26 and aligns it with one of the openings 36 ata heat sink 46, the cover 80 for which is in its closing position. Theemployee inserts the handle 20 of the tray B beneath the upwardly flaredend on the cross wall 84 for the cover 80 in that heat sink 46.Thereupon, the employee advances the tray B into the heat sink 46, withthe lip 14 of the tray B passing beneath the cross wall 84 of the cover80. When the tray B is fully within the heat sink 46, the cross wall 84of the cover 80 establishes a closure over the open top of the tray Band that wall 84 lies over the entire lip 14 along the periphery of thetray B. Moisture remains trapped within the tray B, even though the heatwhich is supplied by the heat sink 46 has the capacity to drive moisturefrom the food. As a consequence, the food in the tray B retains itstaste and texture.

On the other hand, if the tray B contains a food which must remaincrisp, the employee selects a heat sink 46 which has its cover 80 in theventing position. The tray B when aligned with the opening 36 for thisheat sink 46 passes easily into the cavity 48 of the heat sink 46 withlittle manipulation, its lip 14 passing over the shoulders 70 of theheat sink 46 and its bottom wall 2 over the top surface 56 for thebottom wall 50 of the heat sink 46. The cross wall 84 for the cover 80remains well above the lip 14 on the tray B, so that moisture from thefood within the tray B may escape at the open ends of the cover 80, thatis to say over the end walls 6 of the tray B and beneath the cross wall84 of the cover 80.

When the demand for a particular food arises within the restaurant,other employees remove the tray B containing that food from the oven A.This simply involves grasping the tray B by one of its handles 20 andwithdrawing it from its heat sink 46. In this regard, the handles 20project beyond the front and rear panels 28 and 30 of the cabinet 26 andare easily accessible.

Any cover 80 is easily withdrawn from its heat sink 46 by pivoting thestop 88 at the one end of the heat sink 46 away from the opening 36 atthe end of that heat sink 46. This leaves the cavity 48 of the heat sink46 unobstructed, and it is easily cleaned, owing to its continuous andsmooth surfaces. It also enables an employee to easily clean the cover80. And, of course, it permits the employee to reverse the position ofthe cover 80.

The heat sink 46 efficiently transfers heat from its heating element 76to the tray B, thereby keeping the contents of the tray B at a desiredtemperature with minimum expenditure of electrical energy. The foods inthe tray B that are withdrawn, even as long as several hours after beinginserted into the oven A, have essentially the taste and texture thatthey possessed immediately after being cooked. Since the trays B aretotally isolated from each other in the cabinet 26, even when the covers80 over those trays are in their venting positions, flavors are nottransferred between the foods in different trays B.

A modified cover 100 (FIG. 6) has side legs 82 and a cross wall 84 ofessentially the same configuration as their counterparts in the cover80. However, the cross wall 84 contains openings 102 arranged in a rowbetween the legs 82. It also carries a slide 104 which likewise containsopenings 106. The slide 104 is captured on the cross wall 84 such thatit cannot be lifted from the cross wall 84, yet it can slidelongitudinally over the wall 84. Indeed, the slide 104 projects beyondthe ends of the cross wall 84, so that it can be manipulated from theexterior of the oven A to assume various positions on the cross wall 84.In one position, the slide completely covers the openings 102 in thewall 84, and in this position the tray B is sealed. In other positionsthe slide 104 exposes the openings 102 in the wall 84 through its ownopenings 106, with the amount of exposure being dependent in theposition of the slide 104. In these positions the tray B is vented.

A modified tray C (FIG. 7) may be used in the heat sinks 46 to keepfoods warm, and it is similar to the tray B in all respects, except theprovision for removing it from and inserting it into the heat sink 46.Whereas the tray B has handles 20 that are generally flat and extend thefull width of the tray B, the tray C has handles 108 that are narrow andresemble the handles on household frying or sauce pans. The handles 108project from the end walls 6 of the tray C where they are located nearthe peripheral lip 14, but are otherwise centered between the side walls4.

Another modified cover 110 (FIGS. 7 & 8) works well with the tray C, butis also suitable for use with the tray B. The cover 110 has legs 112 anda cross wall 114 extending horizontally between the legs 112 to which itis attached. The legs 112 do not differ from the legs 82 of the cover80, and they rest on the horizontal shoulders 70 of the heat sink 46,even when the tray C is in the cavity 48 of the heat sink 46. Moreover,they extend up to and nearly contact the pan 38 that overlies the heatsink 46 in the cabinet 36. The cross wall 114 has an elevated region 116where it is joined to the legs 112 and a depressed region 118 locatedwithin and being joined to the elevated region 116. The depressed region118 has a peripheral wall 120 that is generally vertical and a bottomwall 122 which lies below, yet parallel to, the surrounding elevatedregion 116.

When the tray C is in the cavity 48 of the heat sink 46 (FIG. 8), thebottom surface of the elevated region 116 in the cross wall 114 liesdirectly above the upper surface 18 on the tray B, there being a gap ofabout 0.375 in. between the two surfaces. The peripheral wall 120, onthe other hand, is set inwardly from the upper surface 18 of the tray Cand inwardly from the upper ends of the side walls 4 and end walls 6 aswell, with the gap being about 0.375 in. The lower surface of the bottomwall 122 lies in a horizontal plane that is slightly above the planedefined by the upper surface 18 on the tray C, with the spacing betweenthe two planes being about 0.01 in. This spacing allows the tray C to beinserted into and removed from the cavity 48 of the heat sink 46 withoutinterference from the cover 110.

At the ends of the cover 110 the elevated region 116 of the cross wall114 turns downwardly in the form of a vertical lip 124, the lower edgeof which lies in the plane of the lower surface on the bottom wall 122.When the tray C is in the heat sink 46, the lips 124 lie slightly beyondthe upper surfaces 18 at the ends of the tray C, yet over or slightlybeyond the depressed edges 16 at those ends. The lips 124 and the nearbysegments of the peripheral wall 120 for the depressed region 118 createlabyrinths which retard moisture from escaping from the tray C.

To enhance the seal established by the lips 124 and the depressed region118 of the cover 110, the lips 124 may be fitted with elastomeric sealelements which bear against the end edges of the laterally directed lip14 of the tray C beyond the two end walls 6 of the tray C. Likewise,elastomeric lip seals may also be fitted to the ends of the cross wallfor the cover 80 to contact the lip 14 at the ends of the tray C andthereby enhance the sealing capabilities of the cover 80.

The rear panel 30 of the cabinet 26, in lieu of having openings 36, maybe solid. In such an arrangement the rear panel 30 would block one endof the cavity 48 for each heat sink 46, and the heat sink 46 itselfcould wrap around the end of the cavity to close it and thus, transferheat to that end wall 6 of the tray B which is presented toward theclosed end. The other end of the heat sink 46 would remain open andindeed would open out of the cabinet 36 through the aligned opening 36in the front panel 28. Of course, the handle 20 on that end of the trayB which faces the closed end of the heat sink 46 would have to beremoved or reconfigured, so that it will not interfere with the solidrear panel 30.

Also, any tray B or C which must retain moisture may be fitted with aseparate cover, and that would eliminate the need for the covers 80 or110. In this regard, covers are available on the market for thetraditional trays that resemble the trays B and C.

This invention is intended to cover all changes and modifications of theexample of the invention herein chosen for purposes of the disclosurewhich do not constitute departures from the spirit and scope of theinvention.

Duke Manufacturing Company

Re: HOLDING OR COOKING OVEN

A oven

B trays

C tray

2 bottom wall

4 side walls

6 end walls

8 corners

10 offset portion

14 lip

16 depressed edge

18 upper surface

20 handles

22

24

26 cabinet

28 front panel

30 rear panel

32 end panels

34 top panel

36 opening

38 upper pan

40 lower pans

41 lips

42 channels

43 lips

44 rigidifying members

46 heat sink

48 cavity

50 bottom wall

52 side walls

54 flat bottom surface

56 flat top surface

58 lower region

60 flat outside surface

62 contoured inside surface

64 curved corner

66 upper regions

68 offsets

70 flat horizontal shoulders

76 heating element

78 thermal insulation

80 cover

82 legs

84 cross wall

88 stops

90

92 electrical controls

100 modified cover

102 openings

104 slide

106 openings

108 handles

110 modified cover

112 legs

114 cross wall

116 elevated region

118 depressed region

120 peripheral wall

122 bottom wall

124 vertical lip

SEQUENCE LISTING

Not Applicable.

What is claimed is:
 1. In combination with plurality of trays, eachhaving a bottom wall and side and end walls attached to the bottom walland extending upwardly to an upper rim to provide an upwardly openinginterior for holding a food, an oven for transferring heat to theinteriors of the trays and the foods in such interiors, said ovencomprising: a cabinet; a plurality of tray-receiving members in thecabinet, each tray-receiving member having a generally horizontal crosswall and side walls connected to and extending generally vertically fromthe horizontal cross wall to provide a generally U-shaped cross section,each tray-receiving member being open at its ends, the trays being in atleast some of the tray-receiving members such that the side walls of thetrays are along the side walls of the tray-receiving members in whichthey are located, the side walls of the tray-receiving members servingto isolate the interiors of the trays from each other so that theflavors of foods in different trays do not transfer; and an electricheating element positioned in the cabinet to direct heat into the traysin the tray-receiving members.
 2. The combination according to claims 1wherein the side walls of each tray-receiving member have horizontaledges located remote from the horizontal cross wall; and wherein theoven further comprises a horizontal closing wall located in the cabinetalong the horizontal edges of the side walls for at least one of thetray-receiving members for closing the tray-receiving member andpreventing flavors from the foods in the tray that is in said onetray-receiving member from transferring laterally past the horizontaledges of the tray-receiving member.
 3. The combination according toclaim 2 wherein the horizontal edges on the side walls of multipletray-receiving members are located along the horizontal closing wall. 4.The combination according to claim 3 wherein the horizontal closing wallis continuous along the multiple tray-receiving member.
 5. Thecombination according to claim 2 wherein the heating element is locatedalong one of the horizontal walls.
 6. The combination according to claim2 wherein the oven further comprises a heating element located along thehorizontal cross wall and side walls of each tray-receiving member. 7.The combination according to claim 2 wherein the side walls of eachtray-receiving member have upper and lower regions and horizontaloffsets between the upper and lower regions; and wherein the tray thatis within the tray-receiving member has its rim located along theoffset.
 8. The combination according to claim 7 wherein the rim of eachtray includes a lip which projects laterally from the side walls andlies along the horizontal offsets of the tray-receiving member in whichthe tray is located.
 9. In combination with a plurality of trays, eachhaving a bottom wall and side and end walls attached to the bottom walland extending upwardly to a laterally directed lip to provide anupwardly opening interior for holding food, an oven for transferringheat to the interiors of the trays and the foods in such interiors, saidoven comprising: a cabinet; first and second members within the cabinetto define open-ended enclosures for receiving the trays, each firstmember being generally U-shaped in cross-section and including ahorizontal cross wall and side walls extending generally vertically fromthe horizontal cross wall, the second member providing a cross wall thatextends generally horizontally between the side walls of at least onefirst member and is spaced from the horizontal cross wall of the firstmember to complete an enclosure in which one of the trays is located,whereby the trays in different enclosures are isolated from each otherand flavors do not transfer laterally within the oven from the food inone tray to the foods in other trays; and a heating element locatedalong one of the horizontal cross walls at each enclosure for heating atray in the enclosure.
 10. The combination according to claim 9 whereinthe side walls of each first member have regions that are remote fromthe cross wall for that first member and the cross wall provided by thesecond member extends between the remote regions of the side walls forthe first member.
 11. The combination according to claim 10 whereinheating element at each enclosure also extends along the side walls forthe first member at that enclosure.
 12. The combination according toclaim 9 wherein the side walls of each first member have upper and lowerregions and horizontal offsets between the upper and lower regions; andwherein the tray that is within the enclosure formed in part by thefirst member has its lips located along the offset.
 13. The combinationaccording to claim 9 wherein the second member provides a cross wall forseveral first members.
 14. The combination according to claim 9 whereinthe heating elements at each enclosure are controlled independently. 15.The combination comprising: a cabinet; a plurality of heat sinks in thecabinet each heat sink being formed from a good conductor of heat andhaving a bottom wall and side walls that extend upwardly from the bottomwall and together with the bottom wall define a cavity having ends, atleast one of which opens out of the heat sink; a heating element on eachheat sink for elevating the temperature of the heat sink, each heatingelement being controlled individually for controlling the temperature ofits heat sink; and at least one food container located in the cavity ofone of the heat sinks, the food container having a bottom wall that islocated along the bottom wall of the heat sink, side walls that extendupwardly from the container bottom wall and are located along the sidewalls of the heat sink, and end walls that extend upwardly from thecontainer bottom wall and connect the container side walls, whereby heatfrom the heat sink is transferred to the food container.